Injection needles are known for injecting medication or anesthetic to a patient. The known injection needles generally are tubular hollow cylindrical bodies having a penetrating end. Such penetrating ends are generally formed by slicing the hollow tubular needle body at an angle. This provides a sharper, reduced area for breaking of the tissue to ease insertion of the needle. Reference is made to the following patents for further background information concerning the injection needles of the prior art: U.S. Pat. Nos. 2,409,979; 2,711,733; 2,717,600; 3,064,651; 3,071,135; and 3,093,134.
The present invention is concerned with the provision of hypotraumatic injection needles, particularly hypotraumatic injection needles adapted for use in ophthalmic surgery. In many opthalmic surgical procedures, such as cataract surgery, it is necessary to inject a local anesthetic in the orbit (i.e., eye socket) behind the globe (i.e., eyeball). This is a very delicate procedure, since a misplacement of the needle can result in serious damage to the eyeball and/or the optical nerve. Moreover, the anesthetic must be injected in a very specific location behind the eyeball in order to properly anesthetize the eyeball and adjacent tissue.
One of the hazards of injecting anesthesia behind the eyeball, which may also be referred to as a "retrobulbar" injection, is that the injection needle may severe or otherwise damage the optic nerve. Such damage to the optic nerve may result in a partial or total loss of vision of the eye, depending on the extent of the damage to the optic nerve.
Another hazard associated with retrobulbar injections is that the injection needle may inadvertently come into contact with the eyeball and cut ocular tissue. This is a significant hazard, because any cutting of ocular tissue creates a risk that an ocular infection will develop; moreover, a serious cut may directly damage the vision of the patient by, for example, injuring the cornea. The above-described hazard also exists in connection with other types of injections in and around the eye, which may be referred to as "peribulbar" injections.